2012 Toyota Prius Plug-in Review By Carey Russ

After a dozen years, three generations (in the U.S, one more
in Japan), and over a million examples sold, the Toyota Prius
gasoline-electric hybrid is hardly advanced technology for early adopters.
It's solidly mainstream, even though it continues to evolve.

Part of that evolution is an expanded model lineup, with the
core sedan, now called the Liftback, joined in the past year by the larger
Prius v, smaller Prius c, and nearly identical-looking Plug-in Hybrid.

Of that group, the Plug-in Hybrid is the most technically
advanced, and presages future evolution for the Prius. But what is meant by
"plug-in hybrid" and isn't the rationale behind an
internal-combustion/electric hybrid vehicle independence from external
charging?

Think of a plug-in hybrid as a vehicle that combines the
best features of a hybrid and a pure electric vehicle (EV). It can operate
further on electricity than a regular hybrid, and that electricity can be
acquired from an external source -- that may be less expensive than
gasoline. When the plug-in battery's charge drops too low, no range anxiety
-- the internal combustion engine will recharge the battery pack and help
run the car, just as in a regular hybrid.

The regular Prius models use a nickel-metal hydride (NiMH)
battery pack that is not amenable to external charging. Older Priuses have
been converted to plug-in operation by independent modification firms, but
there's no factory support if the modifier should go out of business.
Toyota itself had a test program, with 125 2011 Priuses factory-modified
for plug-in operation. Those cars had extra lithium-ion (Li-ion) batteries
in addition to the NiMH battery pack for plug-in operation. I had one as a
test car for a week last year, and found it to be little different from a
regular Prius with the exception of greater EV range and easy at-home
recharging.

Experience with that test fleet went into development of the
official plug-in model. Which is a bit different from both the prototypes
and the regular Prius. In the official plug-in, the NiMH battery pack is
replaced by a Li-ion pack of greater capacity than the "add-on" pack of the
prototypes. It's lighter in weight than the prototype battery pack, but
enables a potentially-longer EV range. When the charge drops to a specified
point, the Plug-in Prius reverts to default hybrid mode, identical to a
standard Liftback. Because of the lighter battery pack and structural
changes including a floor panel made of a reinforced honeycomb-like
material, the Plug-in is about 200 pounds lighter than the prototype
version, and only 120 pounds heavier than the standard Liftback. The rest
of the Plug-in's Hybrid Synergy Drive is the same as the Liftback's, with a
98-horsepower, 1.8-liter Atkinson-cycle four-cylinder gasoline engine, an
80-hp traction motor, and a smaller starter-motor/generator. Maximum system
horsepower is the same 134 as the Liftback. Like other Priuses, it recovers
electrical energy by regenerative braking, with extra regenerative braking
available by moving the shifter to the "B" position.

There are two trim levels, standard and Advanced. The
standard model is equivalent in appointment with the Liftback Two, but with
additional features from the Three and Four. The Advanced gets a Head-up
display, LED headlights, SofTex seating with a power driver's seat, and
upgraded audio system, and the Pre-Collision System with Dynamic Radar
Cruise Control and the Safety Connect telematics system.

My test car was a standard model with minimal options. Not
fancy, but definitely functional -- and lighter than one with all the
options so a bit quicker and more economical. The driving experience is
identical to that of a standard Liftback with one important difference --
beside the Eco and Power mode switches on the console is one marked HV/EV.
As in "Hybrid Vehicle/Electric Vehicle". Default is for the car to start in
EV mode and run as such until the battery reached the cutoff point, at
which time it reverts to normal hybrid mode. If you'll be driving in a
situation that's not ideal for EV mode, like on the highway, defer EV
operation until the conditions are better.

Performance is more than adequate, and in Power mode
acceleration is surprisingly quick. Using Eco mode most of the time, and EV
when most useful, I averaged 53 mpg for my week. Best non-EV mileage was
downhill at a slow speed, with well over 100 mpg showing. Of course, going
up that hill was not quite like that‚€¶¬ and no matter what your
power source, you'll use more energy going up than down.

At $32,000, the Prius Plug-in does command a high (about
$7,000) premium over a Prius Liftback Two or Three. That money still buys
plenty of unleaded regular so a Plug-in is not for everyone. Yet, as
battery technology improves and prices come down, there will be an
increasing number of plug-in hybrids. The system works, and well.

Final note -- I had no problem recharging the Plug-in Prius
at home. Unplug the dryer, plug in the charger, run the cord out the window
to the driveway. And with the charge port repositioned to the right side,
less distance to it. If it can work with my 1943-spec house wiring, it
should work pretty much anywhere!

APPEARANCE: Differences between a Prius Liftback and
Plug-in are minimal. Most apparent is the charge port door on the right
rear fender, complementing the fuel door on the right rear. Badging, on the
front fenders and tail, is unique, with a plug-shaped motif. There's a
chrome panel above the lower air intake in front, and matte silver-finished
outside door handles. Blue-accent headlights and LED taillights further
distinguish the Plug-in.

COMFORT: Interior differences are even less than exterior.
There's a "Plug-in Hybrid" badge on the dash in front of the front
passenger. Fit and finish is as expected from Toyota, first-rate. As are
the materials, textured hard and softish plastics for most surfaces and
carbon-neutral "ecological plastic" for seat foam and some trim pieces.
All of the expected conveniences are here, including a navigation system,
backup camera, AM/FM/SiriusXM radio, CD changer, and connection for iPods
and other external audio players. Plus the Entune multimedia system that
allows use of mobile apps with a smartphone. As in the regular Liftback,
there's more interior space than might be expected, front and rear. The
rear seat folds 60/40 but don't look under the rear load floor for a spare
tire - weight savings means runflats or a can of sealant. There is a small
compartment under the rear of the load floor for the charger cord.

SAFETY: The Prius Plug-in is a Toyota, so it has the
StarSafety System, comprised of vehicle stability control (VSC),
traction control (TRAC), antilock brakes (ABS), electronic brake-force
distribution (EBD), Brake Assist, and the Smart Stop Technology brake
override system. Seven airbags are standard. The Pre-Collision System with
Dynamic Radar Cruise Control and Safety Connect are standard in Advanced
models.

RIDE AND HANDLING: Because of the new battery pack, weight
is increased over the Liftback by about 120 pounds. The suspension is
retuned a bit, and and feels softer than a Liftback. The emphasis in on
comfort, not performance, and the smooth ride and near-silent operation
ensure that. Low rolling resistance tires are meant for maximum mileage,
and do have lower limits of adhesion than performance tires. This is an
ultra-economical family car, not a Toyota Le Mans hybrid prototype race
car‚€¶ and it feels pretty much like a Prius Liftback.

PERFORMANCE: Toyota keeps refining its Hybrid Synergy Drive
system to use electric power instead of internal combustion at higher
speeds and for longer distances. Even in HV mode, the Plug-in runs silently
under electric power more than older Priuses, especially on level ground
under light throttle, or downhill. Engine noise and vibration are minimal,
really only noticeable when starting from cold. At low speeds in EV mode,
the car emits a strange, low-pitched whirring noise, presumably to alert
pedestrians, especially blind ones with excellent hearing. Acceleration,
especially in Power mode, is more than adequate to deal with short on-ramps
and such traffic hazards, and if a newer Prius is acting like a left-lane
bandit, blame the operator, not the car. Braking is exemplary, with
regenerative braking adding to the four-wheel antilock discs.

But the Plug-in's chief attraction is fuel economy. With an EV range
of 10 to 15 miles and a recharge time of three hours (at 120VAC, less for
220), it is possible to rarely use gasoline if the car is used for a short
commute or local errands -- especially if charging is available at the
destination. Even using gasoline, over 50 mpg is readily achieved. Because
it's a hybrid, there is no EV "range anxiety". When the plug-in charge is
used up, it reverts to regular hybrid mode. Just don't run out of gas!

Note that in EV mode, the engine will turn on and add power under
hard acceleration, as in merging on to the highway. I found that at speeds
of 25 mph or less in EV mode, steep hills did not require internal
combustion assistance, at least until the battery drained.

What does charging cost? The Plug-in charges at 1 kilowatt-hour
(kwh). My electric rate is about $0.13/kwh. Three kwh for a full charge is
$0.39. Figure 11 miles (on average) per full charge and that's about three
and half cents per mile! Gasoline? For simplicity, $5.00/gallon
(yes, that's California designer gasoline) and 50 mpg is ten cents a mile.

CONCLUSIONS: Go further on less fuel and recharge easily at
home with the Toyota Prius Plug-in Hybrid.